Polyarylene copolymers and proton-conductive membrane

ABSTRACT

A polyarylene copolymer which comprises (A) aromatic compound units having a main chain containing one or more electron-withdrawing groups therein and (B) aromatic compound units having a main chain containing no electron-withdrawing groups therein, and a proton-conductive membrane comprising the polyarylene copolymer having sulfonic acid groups.

CROSS-REFERENCE TO THE RELATED APPLICATION

[0001] This application is a continuation-in-part application ofapplication Ser. No. 09/818,847 filed Mar. 28, 2001, entitled“POLYARYLENE COPOLYMERS AND PROTON-CONDUCTIVE MEMBRANE”, now pending.

FIELD OF THE INVENTION

[0002] The present invention relates to polyarylene copolymers. Moreparticularly, the invention relates to a polyarylene copolymers usefulas a proton-conductive membrane utilizable in applications such aselectrolytes for primary batteries, electrolytes for secondarybatteries, solid polymer electrolytes for fuel cells, display elements,various sensors, signal-transmitting media, solid capacitors, andion-exchange membranes. The invention further relates to aproton-conductive membrane formed from the copolymer.

DESCRIPTION OF THE RELATED ART

[0003] Electrolytes are usually used as (aqueous) solutions in manycases. In recent years, however, there is a growing tendency to replacesuch aqueous soluble-form electrolytes with solid electrolytes. Thefirst reason for this is the easiness of processing in applications ofsolid electrolytes to, e.g., the electrical/electronic materialsmentioned above. The second reason is the trend toward reduction inweight, thickness, length and size, and toward energy saving.

[0004] Conventional proton-conductive materials include both inorganicmaterials and organic materials. Examples of the inorganic materialsinclude uranyl phosphates which form hydrate. However, these inorganiccompounds are insufficient in interfacial contact to pose many problemsconcerning the formation of a conductive layer on a substrate orelectrode.

[0005] On the other hand, examples of the organic compounds includeorganic polymers such as polymers belonging to the so-calledcation-exchange resins, e.g., sulfonated vinyl polymers such assulfonated polystyrene (co)polymers with perfluoroalkylsulfonic acidrepresented by Nafion (manufactured by E.I. du Pont de Nemours & Co.,Inc.), and perfluoroalkylcarboxylic acid polymers, and polymers preparedwith incorporating sulfonic acid groups or phosphonic acid groups intoheat-resistant polymers such as polybenzimidazole andpoly(ether-ether-ketone)s [see Polymer Preprints, Japan, Vol.42, No.7,pp.2490-2492 (1993); Polymer Preprints, Japan, Vol.43, No.3, pp.735-736(1994); and Polymer Preprints, Japan, Vol.42, No.3, p.730 (1993)].

[0006] Although these organic polymers are usually used in the form of amembrane, a conductive membrane thereof can be bonded to an electrodewhile taking advantage of the solvent-soluble or thermoplasticitythereof. However, many of those organic polymers have the followingproblems besides being still insufficient in proton conductivity. Theorganic polymers deteriorate in mechanical properties and durability orin proton conductivity at elevated temperatures (100° C. or higher), andthe proton conductivity thereof highly depends on humidity conditions.Adhesion to the electrode is not fully satisfactory. Furthermore, theconductive membrane swells excessively during operation due to thehydrophilic polymer structure, and this swelling leads to a decrease instrength properties or a deformation. Consequently, application of thoseorganic polymers to the aforementioned electrical/electronic materialsand the like pose various problems.

[0007] U.S. Pat. No. 5,403,675 proposes a solid polymer electrolytecomprising a sulfonated rigid polyphenylene. This polymer is producedfrom a polymer comprising a phenylene chain obtained by polymerizing anaromatic compound (the polymer structure is described in column 9 in thespecification) by reacting the phenylene polymer as the main componentwith a sulfonating agent to incorporate sulfonic acid groups thereinto.However, the incorporation of a large amount of sulfonic acid groupsresults in a sulfonated polymer having considerably impaired mechanicalstrength properties although proton conductivity improves with theincreasing amount of sulfonic acid groups incorporated. It is thereforenecessary to regulate the concentration of sulfonic acid groups to aproper value which enables the sulfonated polymer to retain intactexcellent mechanical properties and have proton conductivity. Virtually,however, sulfonation of this polymer is apt to proceed excessively andit is exceedingly difficult to properly regulate the amount of sulfonicgroups incorporated.

SUMMARY OF THE INVENTION

[0008] The invention has been achieved in view of the conventionaltechnical problems.

[0009] One object of the invention is to provide polyarylene copolymerswhich can be sulfonated while being easily regulated with respect to theupper limit of sulfonic acid group incorporation amount so as not toimpair mechanical properties and thus gives a sulfonated polymer whichhas high proton conductivity in a wide temperature range, has excellentmechanical strength, is reduced in swelling in hot water, and gives aproton-conductive membrane having excellent durability.

[0010] Another object of the invention is to provide a proton-conductivemembrane formed from the copolymer.

[0011] The invention provides polyarylene copolymers which comprise (A)aromatic compound units having a main chain containing one or moreelectron-withdrawing groups and one or more ether bonds therein(hereinafter referred to also as “units (A)”) and (B) aromatic compoundunits having a main chain containing no electron-withdrawing groupstherein.

[0012] The electron-withdrawing groups preferably are divalent groupswhich are at least one member selected from the group consisting of—CO—, —CONH—, —(CF₂)_(p)— (wherein p is an integer of 1 to 10),—C(CF₃)₂—, —COO—, —SO—, and —SO₂—.

[0013] The polyarylene copolymer of the invention preferably arepolyarylene copolymers having sulfonic acid groups (hereinafter referredto also as “sulfonic acid-containing copolymer” or “sulfonatedpolymer”).

[0014] The invention further provides proton-conductive membranescomprising the sulfonic acid-containing copolymers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is an IR chart of the sulfonated polymer obtained inExample 1.

[0016]FIG. 2 is an IR chart of the sulfonated polymer obtained inExample 2.

[0017]FIG. 3 is an IR chart of the sulfonated polymer obtained inExample 3.

[0018]FIG. 4 is an IR chart of the polyarylene copolymer obtained inExample 4.

[0019]FIG. 5 is an IR chart of the sulfonated polymer obtained inExample 5.

[0020]FIG. 6 is an IR chart of the polyarylene obtained in Example 6.

[0021]FIG. 7 is an IR chart of the sulfonated polymer obtained inExample 6.

[0022]FIG. 8 is an IR chart of the polyarylene obtained in Example 8.

[0023]FIG. 9 is an IR chart of the sulfonated polymer obtained inExample 8.

[0024]FIG. 10 is an IR chart of the polyarylene obtained in Example 10.

[0025]FIG. 11 is an IR chart of the sulfonated polymer obtained inExample 10.

[0026]FIG. 12 is an IR chart of the polyarylene obtained in Example 11.

[0027]FIG. 13 is an IR chart of the sulfonated polymer obtained inExample 11.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The polyarylene copolymer of the invention comprises (A) aromaticcompound units having a main chain containing one or moreelectron-withdrawing groups therein and (B) aromatic compound unitshaving a main chain containing no electron-withdrawing groups therein.

[0029] Examples of units (A) include aromatic compound units representedby the following general formula (1), while examples of units (B)include aromatic compound units represented by at least one of thefollowing formulae (2) to (4).

[0030] The term “electron-withdrawing group” as used herein means agroup having a Hammett's substituent constant of 0.06 or larger or 0.01or larger when located in a meta position or the para position,respectively, in the phenyl group.

[0031] wherein X and X′ may be the same or different and each representsat least one divalent electron-withdrawing group selected from the groupconsisting of —CO—, —CONH—, —(CF₂)_(p)—(wherein p is an integer of 1 to10), —C(CF₃)₂—, —COO—, —SO—, and —SO₂—; R¹ to R¹⁶ may be the same ordifferent and each represents a hydrogen atom, a halogen atom, an alkylgroup, a halogenoalkyl group, an allyl group, or an aryl group; and n isa number of 0 or 1.

[0032] in general formulae (2) to (4), R¹⁷ to R²⁴ may be the same ordifferent and each represents a hydrogen atom, an alkyl group, a halogenatom, a halogenoalkyl group, an aryl group, or a group represented bythe formula

[0033] wherein X represents an electron-withdrawing divalent group; Yrepresents an electron-donating divalent group; and R²⁵ to R³³ eachrepresents a hydrogen atom, an alkyl group, a halogen atom, ahalogenoalkyl group, or an aryl group.

[0034] Specific examples of R¹ to R¹⁶ in general formula (1) are asfollows. Examples of the halogen atom include fluorine atom. Examples ofthe alkyl group include methyl and ethyl. Examples of the halogenoalkylgroup include trifluoromethyl and pentafluoroethyl. Examples of theallyl group include propenyl. Examples of the aryl group include phenyland pentafluorophenyl.

[0035] In general formulae (2) to (4), R¹⁷ to R²⁴ may be the same ordifferent and represent a hydrogen atom, an alkyl group, a halogen atom,a halogenoalkyl group, or a monovalent organic group containing one ormore functional groups which do not inhibit a polyarylene-polymerizationreaction.

[0036] Examples of the alkyl group represented by R¹⁷ to R²⁴ includemethyl, ethyl, propyl, butyl, pentyl, and hexyl.

[0037] Examples of the halogen atom include chlorine, bromine, andiodine atoms. Examples of the halogenoalkyl group includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl,perfluoropentyl, and perfluorohexyl.

[0038] In the formula

[0039] examples of the electron-withdrawing group represented by Xinclude the same electron-withdrawing groups enumerated above withregard to general formula (1), and examples of the electron-withdrawinggroup represented by Y include —O— and —S—. Specific examples of thegroup represented by the formula include 4-phenoxyphenylcarbonyl.

[0040] In the polyarylene copolymers of the invention, the proportion ofunits (A) is 60 mol % or less, preferably from 60 to 0.01 mol %, morepreferably from 40 to 0.01 mol %.

[0041] If the proportion of units (A) exceeds 60 mol %, not only thepolyarylene copolymers obtained have poor solubility leadedprocessability, but also sulfonic acid groups cannot be incorporatedafter polymerization in an amount sufficient to enable the polymer tohave proton conductivity.

[0042] The polyarylene copolymers of the invention comprise repeatingstructural units represented by general formula (1) given above [units(A)] and repeating structural units represented by at least one ofgeneral formulae (2) to (4) given above [units (B)].

[0043] The sulfonic acid-containing copolymers are, for example,polymers obtained by copolymerizing a monomer corresponding to generalformula (1) with one or more monomers corresponding to at least one ofgeneral formulae (2) to (4) in the presence of a catalyst comprising atransition metal compound and sulfonating the resultant copolymers witha sulfonating agent.

[0044] The polyarylene copolymers of the invention are prepared, forexample, with polymerizing an aromatic compound which has a main chaincontaining one or more electron-withdrawing groups and one or more etherbonds therein and is represented by the following general formula (1)′(hereinafter referred to also as “monomer (A)”) with at least onearomatic compound represented by at least one of the following generalformulae (2)′ to (4)′ (hereinafter referred to also as “monomer (B)”) ina solvent in the presence of a catalyst comprising a transition metalcompound.

[0045] In general formula (1)′ given above, X, X′, R¹ to R¹⁶, and n arethe same as in general formula (1); and R and R′ may be the same ordifferent and each represents a halogen atom other than fluorine or agroup represented by —OSO₂Z (wherein Z represents an alkyl group, ahalogenoalkyl group, or an aryl group).

[0046] Examples of the halogen atom represented by R or R′ in generalformula (1)′ include chlorine, bromine, and iodine atoms. In the group—OSO₂Z in general formula (1)′, examples of the alkyl group representedby Z include methyl and ethyl, examples of the halogenoalkyl grouprepresented thereby include trifluoromethyl, and examples grouprepresented thereby include phenyl and p-tolyl.

[0047] In general formulae (2)′ to (4)′, R¹⁷ to R²⁴ are the same as ingeneral formulae (2) to (4), and R and R′ are the same as in generalformula (1)′.

[0048] Examples of the monomers (A) represented by general formula (1)′include

[0049] 4,4′-dichlorobenzophenone, 2,4′-dichlorobenzophenone,3,3′-dichlorobenzophenone,

[0050] 4,4′-dibromobenzophenone, 2,4′-dibromobenzophenone,3,3′-dibromobenzophenone,

[0051] 4,4′-diiodobenzophenone, 2,4′-diiodobenzophenone,3,3′-diiodobenzophenone,

[0052] bis(4-trifluoromethylsulfonyloxyphenyl) ketone,

[0053] bis(3-trifluoromethylsulfonyloxy-phenyl) ketone,

[0054] 4,4′-bis(4-chlorobenzoyl)diphenyl ether,

[0055] 4,4′-bis(3-chlorobenzoyl)diphenyl ether,4,4′-bis(4-bromobenzoyl)diphenyl ether,

[0056] 4,4′-bis(3-bromobenzoyl)diphenyl ether,4,4′-bis(4-iodobenzoyl)diphenyl ether,

[0057] 4,4′-bis(3-iodobenzoyl)diphenyl ether,

[0058] 4,4′-bis(4-trifluoromethylsulfonyloxyphenyl)diphenyl ether,

[0059] 4,4′-bis(3-trifluoromethylsulfonyloxyphenyl)diphenyl ether,

[0060] 4,4′-bis(4-methylsulfonyloxyphenyl)diphenyl ether,

[0061] 4,4′-bis(3-methylsulfonyloxyphenyl)diphenyl ether,

[0062] 4′-bis(4-chlorobenzoylamino)diphenyl ether,

[0063] 3,4′-bis(4-chlorobenzoylamino)diphenyl ether,

[0064] 4,4′-bis(3-chlorobenzoylamino)diphenyl ether,3,4′-bis(3-chlorobenzoyl)diphenyl ether,

[0065] 4,4′-bis(4-bromobenzoylamino)diphenyl ether,

[0066] 3,4′-bis(4-bromobenzoylamino)diphenyl ether,

[0067] 4,4′-bis(3-bromobenzoylamino)diphenyl ether,

[0068] 3,4′-bis(3-bromobenzoylamino)diphenyl ether,

[0069] 4,4′-bis(4-iodobenzoylamino)diphenyl ether,

[0070] 3,4′-bis(4-iodobenzoylamino)diphenyl ether,

[0071] 4,4′-bis(3-iodobenzoylamino)diphenyl ether,

[0072] 3,4′-bis(3-iodobenzoylamino)diphenyl ether,

[0073] 4,4′-bis(4-trifluoromethylsulfonyloxyphenyl)diphenyl ether,

[0074] 3,4′-bis(4-trifluoromethylsulfonyloxyphenyl)diphenyl ether,

[0075] 4,4′-bis(3-trifluoromethylsulfonyloxyphenyl)diphenyl ether,

[0076] 3,4′-bis(3-trifluoromethylsulfonyloxyphenyl)diphenyl ether,

[0077] 4,4′-bis(4-methylsulfonyloxyphenyl)diphenyl ether,

[0078] 3,4′-bis(4-methylsulfonyloxyphenyl)diphenyl ether,

[0079] 4,4′-bis(3-methylsulfonyloxyphenyl)diphenyl ether,

[0080] 3,4′-bis(3-methylsulfonyloxyphenyl)diphenyl ether,

[0081] 4,4′-bis(4-chlorophenylsulfonyl)diphenyl ether,

[0082] 3,4′-bis(4-chlorophenylsulfonyl)diphenyl ether,

[0083] 4,4′-bis(3-chlorophenylsulfonyl)diphenyl ether,

[0084] 3,4′-bis(3-chlorophenylsulfonyl)diphenyl ether,

[0085] 4,4′-bis(4-bromophenylsulfonyl)diphenyl ether,

[0086] 4,4′-bis(4-bromophenylsulfonyl)diphenyl ether,

[0087] 4,4′-bis(3-bromophenylsulfonyl)diphenyl ether,

[0088] 3,4′-bis(3-bromophenylsulfonyl)diphenyl ether,

[0089] 4,4′-bis(4-iodophenylsulfonyl)diphenyl ether,

[0090] 4,4′-bis(4-iodophenylsulfonyl)diphenyl ether,

[0091] 4,4′-bis(3-iodophenylsulfonyl)diphenyl ether,

[0092] 3,4′-bis(3-iodophenylsulfonyl)diphenyl ether,

[0093] 4,4′-bis(4-trifluoromethylsulfonyloxyphenylsulfonyl)diphenylether,

[0094] 4,4′-bis(4-trifluoromethylsulfonyloxyphenylsulfonyl)diphenylether,

[0095] 4,4′-bis(3-trifluoromethylsulfonyloxyphenylsulfonyl)-diphenylether,

[0096] 3,4′-bis(3-trifluoromethylsulfonyloxyphenylsulfonyl)-diphenylether,

[0097] 4,4′-bis(4-methylsulfonyloxyphenylsulfonyl)-diphenyl ether,

[0098] 4,4′-bis(4-methylsulfonyloxyphenylsulfonyl)-diphenyl ether,

[0099] 4,4′-bis(3-methylsulfonyloxyphenylsulfonyl)-diphenyl ether,

[0100] 3,4′-bis(3-methylsulfonyloxyphenylsulfonyl)-diphenyl ether,

[0101] 4,4′-bis(4-chlorophenyl)diphenyl ether dicarboxylate,

[0102] 3,4′-bis(4-chlorophenyl)diphenyl ether dicarboxylate,

[0103] 4,4′-bis(3-chlorophenyl)diphenyl ether dicarboxylate,

[0104] 3,4′-bis(3-chlorophenyl)diphenyl ether dicarboxylate,

[0105] 4,4′-bis(4-bromophenyl)diphenyl ether dicarboxylate,

[0106] 3,4′-bis(4-bromophenyl)diphenyl ether dicarboxylate,

[0107] 4,4′-bis(3-bromophenyl)diphenyl ether dicarboxylate,

[0108] 3,4′-bis(3-bromophenyl)diphenyl ether dicarboxylate,

[0109] 4,4′-bis(4-iodophenyl)diphenyl ether dicarboxylate,

[0110] 3,4′-bis(4-iodophenyl)diphenyl ether dicarboxylate,

[0111] 4,4′-bis(3-iodophenyl)diphenyl ether dicarboxylate,

[0112] 3,4′-bis(3-iodophenyl)diphenyl ether dicarboxylate,

[0113] 4,4′-bis(4-trifluoromethylsulfonyloxyphenyl)diphenyl etherdicarboxylate,

[0114] b 3,4′-bis(4-trifluoromethylsulfonyloxyphenyl)diphenyl etherdicarboxylate,

[0115] 4,4′-bis(3-trifluoromethylsulfonyloxyphenyl)diphenyl etherdicarboxylate,

[0116] 3,4′-bis(3-trifluoromethylsulfonyloxyphenyl)diphenyl etherdicarboxylate,

[0117]4,4′-bis(4-methylsulfonyloxyphenyl)diphenyl ether dicarboxylate,

[0118] 3,4′-bis(4-methylsulfonyloxyphenyl)diphenyl ether dicarboxylate,

[0119] 4,4′-bis(3-methylsulfonyloxyphenyl)diphenyl ether dicarboxylate,

[0120] 3,4′-bis(3-methylsulfonyloxyphenyl)diphenyl ether dicarboxylate,

[0121] 4,4′-bis[(4-chlorophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0122] 3,4′-bis[(4-chlorophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0123] 4,4′-bis[(3-chlorophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0124] 3,4′-bis[(3-chlorophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0125] 4,4′-bis[(4-bromophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0126] 3,4′-bis[(4-bromophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0127] 4,4′-bis[(3-bromophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0128] 3,4′-bis[(3-bromophenyl)-1,1,1,3,3,3-hexafluoropropyl] diphenylether,

[0129] 4,4′-bis[(4-iodophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0130] 3,4′-bis[(4-iodophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0131] 4,4′-bis[(3-iodophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0132] 3,4′-bis[(3-iodophenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0133]4,4′-bis[(4-trifluoromethylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0134]3,4′-bis[(4-trifluoromethylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0135]4,4′-bis[(3-trifluoromethylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0136] 3,4′-bis[(3-trifluoromethylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0137]4,4′-bis[(4-methylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0138]3,4′-bis[(4-methylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0139]4,4′-bis[(3-methylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0140]3,4′-bis[(3-methylsulfonyloxyphenyl)-1,1,1,3,3,3-hexafluoropropyl]diphenylether,

[0141] 4,4′-bis[(4-chlorophenyl)tetrafluoroethyl]diphenyl ether,

[0142] 4,4′-bis[(3-chlorophenyl)tetrafluoroethyl]diphenyl ether,

[0143] 4,4′-bis[(4-chlorophenyl)hexafluoropropyl]diphenyl ether,

[0144] 4,4′-bis[(3-chlorophenyl)hexafluoropropyl]diphenyl ether,

[0145] 4,4′-bis[(4-chlorophenyl)octafluorobutyl]diphenyl ether,

[0146] 4,4′-bis[(3-chlorophenyl)octafluorobutyl]diphenyl ether,

[0147] 4,4′-bis[(4-chlorophenyl)decafluoropentyl]diphenyl ether,

[0148] 4,4′-bis[(3-chlorophenyl)decafluoropentyl]diphenyl ether,

[0149] 4,4′-bis[(4-bromophenyl)tetrafluoroethyl]diphenyl ether,

[0150] 4,4′-bis[(3-bromophenyl)tetrafluoroethyl]diphenyl ether,

[0151] 4,4′-bis[(4-bromophenyl)hexafluoropropyl]diphenyl ether,

[0152] 4,4′-bis[(3-bromophenyl)hexafluoropropyl]diphenyl ether,

[0153] 4,4′-bis[(4-bromophenyl)octafluorobutyl]diphenyl ether,

[0154] 4,4′-bis[(3-bromophenyl)octafluorobutyl]diphenyl ether,

[0155] 4,4′-bis[(4-bromophenyl)decafluoropentyl]diphenyl ether,

[0156] 4,4′-bis[(3-bromophenyl)decafluoropentyl]diphenyl ether,

[0157] 4,4′-bis[(4-iodophenyl)tetrafluoroethyl]diphenyl ether,

[0158] 4,4′-bis[(3-iodophenyl)tetrafluoroethyl]diphenyl ether,

[0159] 4,4′-bis[(4-iodophenyl)hexafluoropropyl]diphenyl ether,

[0160] 4,4′-bis[(3-iodophenyl)hexafluoropropyl]diphenyl ether,

[0161] 4,4′-bis[(4-iodophenyl)octafluorobutyl]diphenyl ether,

[0162] 4,4′-bis[(3-iodophenyl)octafluorobutyl]diphenyl ether,

[0163] 4,4′-bis[(4-iodophenyl)decafluoropentyl]diphenyl ether,

[0164] 4,4′-bis[(3-iodophenyl)decafluoropentyl]diphenyl ether,

[0165]4,4′-bis[(4-trifluoromethylsulfonyloxyphenyl)tetrafluoroethyl]iphenylether,

[0166]4,4′-bis[(3-trifluoromethylsulfonyloxy-phenyl)tetrafluoroethyl]diphenylether,

[0167]4,4′-bis[(4-trifluoromethylsulfonyloxyphenyl)hexafluoropropyl]diphenylether,

[0168]4,4′-bis[(3-trifluoromethylsulfonyloxyphenyl)hexafluoropropyl]diphenylether,

[0169]4,4′-bis[(4-trifluoromethylsulfonyloxyphenyl)octafluorobutyl]diphenylether,

[0170]4,4′-bis[(3-trifluoromethylsulfonyloxyphenyl)octafluorobutyl]diphenylether,

[0171]4,4′-bis[(4-trifluoromethylsulfonyloxyphenyl)decafluoropentyl]diphenylether,

[0172]4,4′-bis[(3-trifluoromethylsulfonyloxyphenyl)decafluoropentyl]diphenylether,

[0173] 4,4′-bis[(4-methylsulfonyloxyphenyl)tetrafluoroethyl]diphenylether,

[0174] 4,4′-bis[(3-methylsulfonyloxyphenyl)tetrafluoroethyl]diphenylether,

[0175] 4,4′-bis[(4-methylsulfonyloxyphenyl)-hexafluoropropyl]diphenylether,

[0176] 4,4′-bis[(3-methylsulfonyloxyphenyl)hexafluoropropyl]diphenylether,

[0177] 4,4′-bis[(4-methylsulfonyloxyphenyl)octafluorobutyl]diphenylether,

[0178] 4,4′-bis[(3-methylsulfonyloxyphenyl)octafluorobutyl]diphenylether,

[0179] 4,4′-bis[(4-methylsulfonyloxyphenyl)-decafluoropentyl]diphenylether, and

[0180] b 4,4′-bis[(3-methylsulfonyloxyphenyl)decafluoropentyl]diphenylether.

[0181] On the other hand, examples of the monomers (B) represented bygeneral formula (2)′ include p-dichlorobenzene, p-dibromobenzene,p-diiodobenzene, p-dimethylsulfonyloxybenzene, 2,5-dichlorotoluene,2,5-dibromotoluene, 2,5-diiodotoluene, 2,5-dimethylsulfonyloxybenzene,2,5-dichloro-p-xylene, 2,5-dibromo-p-xylene, 2,5-diiodo-p-xylene,2,5-dichlorobenzotrifluoride, 2,5-dibromobenzotrifluoride,2,5-diiodobenzotrifluoride, 1,4-dichloro-2,3,5,6-tetrafluorobenzene,1,4-dibromo-2,3,5,6-tetrafluorobenzene,1,4-diiodo-2,3,5,6-tetrafluorobenzene,4′-phenoxy-2,5-dichlorobenzophenone, and 4′-phenoxyphenyl2,5-dichlorobenzoate. Preferred of these are p-dichlorobenzene,p-dimethylsulfonyloxybenzene, 2,5-dichlorotoluene,2,5-dichlorobenzotrifluoride, 4′-phenoxy-2,5-dichlorobenzophenone, and4′-phenoxyphenyl 2,5-dichlorobenzoate.

[0182] Examples of the monomers (B) represented by general formula (3)′include 4,4′-dimethylsulfonyloxybiphenyl,4,4′-dimethylsulfonyloxy-3,3′-dipropenylbiphenyl, 4,4′-dibromobiphenyl,4,4′-diiodobiphenyl, 4,4′-dimethylsulfonyloxy-3,3′-dimethylbiphenyl,4,4′-dimethylsulfonyloxy-3,3′-difluorobiphenyl,4,4′-dimethylsulfonyloxy-3,3′,5,5′-tetrafluorobiphenyl,4,4′-dibromooctafluorobiphenyl, and4,4′-(4-methylsulfonyloxyphenyloctafluorobiphenyl. Preferred of theseare 4,4′-dimethylsulfonyloxybiphenyl, 4,4′-dibromobiphenyl,4,4′-diiodobiphenyl, and4,4′-dimethylsulfonyloxy-3,3′-dipropenylbiphenyl.

[0183] Examples of the monomers (B) represented by general formula (4)′include m-dichlorobenzene, m-dibromobenzene, m-diiodobenzene,m-dimethylsulfonyloxybenzene, 2,4-dichlorotoluene, 2,4-dibromotoluene,2,4-diiodotoluene, 3,5-dichlorotoluene, 3,5-dibromotoluene,3,5-diiodotoluene, 2,6-dichlorotoluene, 2,6-dibromotoluene,2,6-diiodotoluene, 3,5-dimethylsulfonyloxytoluene,2,6-dimethylsulfonyloxytoluene, 2,4-dichlorobenzotrifluoride,2,4-dibromobenzotrifluoride, 2,4-diiodobenzotrifluoride,3,5-dichlorobenzotrifluoride, 3,5-dibromobenzotrifluoride,3,5-diiodobenzotrifluoride, 1,3-dibromo-2,4,5,6-tetrafluorobenzene,2,4-dichloro-4′-phenoxybenzophenone, and 2,4-dichloro-4′-phenoxyphenylbenzoate. Preferred of these are m-dichlorobenzene, 2,4-dichlorotoluene,3,5-dimethylsulfonyloxytoluene, 2,4-dichlorobenzotrifluoride,2,4-dichloro-4′-phenoxybenzophenone, and 2,4-dichloro-4′-phenoxyphenylbenzoate.

[0184] Preferred of the aforementioned monomers (B) represented bygeneral formulae (2)′ to (4)′ from the standpoints of solubility andproduction of a polymer having a high molecular weight are2,5-dichloro-4′-phenoxybenzophenone,2,4-dichloro-4′-phenoxybenzophenone, 2,5-dichloro-4′-phenoxyphenylbenzoate, and 2,4-dichloro-4′-phenoxyphenyl benzoate.

[0185] The proportion of monomers (A), which is at least one compoundrepresented by general formula (1)′, to monomers (B), which is at leastone of aromatic compounds represented by general formulae (2)′ to (4)′,to be copolymerized is the same as the proportion of units (A) to units(B) described above. Namely, monomers (A) is used in an amount of 60 mol% or less, preferably 40 to 0.01 mol %, while monomers (B) is used in anamount of 40 mol % or more, preferably 60 to 99.99 mol %.

[0186] In particular, in the case where monomers (B) represented bygeneral formula (2)′ is used, the proportion thereof is preferably 10mol % or larger, more preferably 20 mol % or larger, based on allmonomers. When the proportion of monomers (B) represented by generalformula (2)′ is within that range, polymers having high molecularweights and satisfactory solubility is obtained.

[0187] In the case where monomers (B) represented by general formula(3)′ is used, the proportion thereof is preferably 50 mol % or smaller,more preferably 30 mol % or smaller, based on all monomers. When theproportion of this monomer is within that range, polymers having highmolecular weights and satisfactory solubility is obtained.

[0188] Furthermore, in the case where monomers (B) represented bygeneral formula (4)′ is used, the proportion thereof is preferably 50mol % or smaller, more preferably 30 mol % or smaller, based on allmonomers.

[0189] The catalyst to be used in producing the polyarylene copolymersof the invention is a catalyst system containing transition metalcompounds. The catalyst systems comprise as essential ingredients (1)either a combination of a transition metal salt and one or more ligandsor a transition metal (salt) having one or more ligands coordinatedthereto and (2) a reducing agent. A salt may be added to the catalystsystem in order to heighten the rate of polymerization.

[0190] Examples of the transition metal salt include nickel compoundssuch as nickel chloride, nickel bromide, nickel iodide, and nickelacetylacetonate, palladium compounds such as palladium chloride,palladium bromide, and palladium iodide, iron compounds such as ironchloride, iron bromide, and iron iodide, and cobalt compounds such ascobalt chloride, cobalt bromide, and cobalt iodide. Especially preferredof these are nickel chloride and nickel bromide.

[0191] Examples of the ligands include triphenylphosphine,2,2′-bipyridine, 1,5-cyclooctadiene, and1,3-bis(diphenylphosphino)propane. Preferred of these aretriphenylphosphine and 2,2′-bipyridine. These ligands may be used aloneor in combination of two or more thereof.

[0192] Examples of the transition metals (salts) having one or moreligands coordinated thereto include nickel chloridebis(triphenylphosphine), nickel bromide bis(triphenylphosphine), nickeliodide bis(triphenylphosphine), nickel nitrate bis(triphenylphosphine),nickel chloride 2,2′-bipyridine, nickel bromide 2,2′-bipyridine, nickeliodide 2,2′-bipyridine, nickel nitrate 2,2′-bipyridine,bis(1,5-cyclooctadiene)nickel, tetrakis(triphenylphosphine)nickel,tetrakis(triphenylphosphite)nickel, andtetrakis(triphenylphosphine)palladium. Preferred of these are nickelchloride bis(triphenylphosphine) and nickel chloride 2,2′-bipyridine.

[0193] Examples of the reducing agents which can be used in the catalystsystems according to the invention include iron, zinc, manganese,aluminum, magnesium, sodium, and calcium. Preferred of these are zinc,magnesium, and manganese. These reducing agents can be used after havingbeen further activated by contact with an acid, e.g., an organic acid.

[0194] Examples of the salts which can be optionally used in thecatalyst systems according to the invention include sodium compoundssuch as sodium fluoride, sodium chloride, sodium bromide, sodium,iodide, and sodium sulfate, potassium compounds such as potassiumfluoride, potassium chloride, potassium bromide, potassium iodide, andpotassium sulfate, and ammonium compounds such as tetraethylammoniumfluoride, tetraethylammonium chloride, tetraethylammonium bromide,tetraethylammonium iodide, and tetraethylammonium sulfate. Preferred ofthese are sodium bromide, sodium iodide, potassium bromide,tetraethylammonium bromide, and tetraethylammonium iodide.

[0195] In the catalyst systems, the proportions of the ingredients to beused therein are as follows. The proportion of either the transitionmetal salts or the transition metals (salts) having one or more ligandscoordinated thereto is generally from 0.0001 to 10 mol, preferably from0.01 to 0.5 mol, per mol of all the monomers represented by generalformulae (1)′ to (4)′. When the proportion thereof is smaller than0.0001 mol, the polymerization reaction does not proceed sufficiently.On the other hand, proportions thereof exceeding 10 mol pose such aproblem that the polymerization yields a polymer having low molecularweight.

[0196] In the case where the catalyst system contains a transition metalsalts and one or more ligands, the proportion of the ligands isgenerally from 0.1 to 100 mol, preferably from 1 to 10 mol, per mol ofthe transition metal salts. When the proportion thereof is smaller than0.1 mol, the result is insufficient catalytic activity. On the otherhand, proportions thereof exceeding 100 mol pose such a problem that thepolymerization yields polymer with a low molecular weight.

[0197] The proportion of the reducing agents to be used in the catalystsystems are generally from 0.1 to 100 mol, preferably from 1 to 10 mol,per mol of all the monomers represented by general formulae (1)′ to(4)′. When the proportion thereof is smaller than 0.1 mol, thepolymerization does not proceed sufficiently. On the other hand,proportions thereof exceeding 100 mol pose a problem that the polymerobtained is difficult to purify.

[0198] In the case where the salts as an optional ingredient are used inthe catalyst system, the proportion thereof is generally from 0.001 to100 mol, preferably from 0.01 to 1 mol, per mol of all the monomersrepresented by general formulae (1)′ to (4)′. When the proportionthereof is smaller than 0.001 mol, the effect of heightening the rate ofpolymerization is insufficient. On the other hand, proportions thereofexceeding 100 mol pose such a problem that the polymer obtained isdifficult to purify.

[0199] In the invention, the monomers (A) and the monomers (B) can bereacted in the presence of a molecular weight modifier, therebycontrolling a molecular weight of the polymer obtained.

[0200] The molecular weight modifier is a monomer having only onereaction site (such as monohalogenated aromatic compounds ormonosulfonate compounds) in order to stop increase in molecular weightof the polyarylene obtained. The molecular weight modifier isrepresented by general formula such as R-φ, R-φ-T or R-φ-T-φ, wherein Ris a group represented by halogen atom or —OSO₂Z (wherein Z representsalkyl group, halogenated alkyl group or aryl group), φ is benzenenucleus, and T is monovalent or divalent electron-withdrawing groups,where examples of the monovalent groups include —CN, —NO₂ and —CONR″₂(wherein R″ represents alkyl group or aryl group), and examples of thedivalent groups include —CO—, —CONH—, —SO₂, —SO—, —C(CF₃)—, —,—C(CF₃)(C₆H₅)—and —COO—.

[0201] Preferable examples of the molecular weight modifier includemonohalogented aromatic compounds such as 4-chlrobenzophenoe,4-chlorobenzanilide, chlrorbenzene, bromobenzene, 4-bromobenzophenone,phenyl 4-chlorobenzoate, phenyl 4-bromobenzoate, 4-chlorophenylbenzoate, 4-bromophenyl benzoate,2,2-chlorophenyl-phenylhexafluoropropane and1,1,1-diphenylchlorophenyltrifluoromethane, and monosulfonate compoundssuch as chlorophenylphenylsulfone, 4-sulfonyloxybenzophenone and4-sulfonylxydiphenylsulfone. In the invention, halogen atom that themonohalogenated aromatic compounds have is preferably chlorine atom orbromine atom.

[0202] Amount of the molecular weight modifier used is 0.1 to 100 mmol,preferably 0.5 to 30.0 mmol, pre mole of the sum of the monomers (A) andmonomers (B). If the amount is less than 0.1 mmol, the effect toincrease molecular weight is not exhibited, and if the amount exceeds100 mmol, molecular weight remarkably decreases.

[0203] Examples of polymerization solvents which can be used in theinvention include tetrahydrofuran, cyclohexanone, dimethyl sulfoxide,N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone andγ-butyrolactam. Preferred of these are tetrahydrofuran,N,N-dimethylformamide, N,N-dimethylacetamide, andN-methyl-2-pyrrolidone. It is preferred to sufficiently dry thesepolymerization solvents before use.

[0204] The concentration of all the monomers represented by generalformulae (1)′ to (4)′ in the polymerization solvent is generally from 1to 90% by weight, preferably from 5 to 40% by weight.

[0205] The polymerization for preparing the polymer of the invention isconducted at a temperature of generally from 0 to 200° C., preferablyfrom 50 to 80° C., for a period of usually from 0.5 to 100 hours,preferably from 1 to 40 hours.

[0206] In the case where monomers (A) represented by general formula(1)′ and monomers (B) represented by general formula (2)′ are used forobtaining a polymer consisting of repeating structural units representedby general formulae (1) and (2) (provided that the units have nosulfonic acid groups), an example of the reaction schemes is as follows.

[0207] The structure of the polyarylene copolymers of the invention canbe ascertained, for example, from infrared absorption spectra based onthe C—O—C stretching appearing at 1,230 to 1,250 cm⁻¹, the C═Ostretching appearing at 1,640 to 1,660 cm⁻¹, etc., or from a nuclearmagnetic resonance (¹H-NMR) based on the peak assigned to aromaticprotons appearing at 6.8 to 8.0 ppm.

[0208] The polyarylene copolymers having sulfonic acid groups for use asthe conductive membrane of the invention can be obtained byincorporating sulfonic acid groups into the above-described polyarylenecopolymers having no sulfonic acid groups by an ordinary method using asulfonating agent.

[0209] For example, sulfonic acid groups can be incorporated bysulfonating the polyarylene copolymers having no sulfonic acid groupswith known sulfonating agents such as sulfuric acid anhydride, fumingsulfuric acid, chlorosulfonic acid, sulfuric acid, or sodium hydrogensulfite under known conditions [see Polymer Preprints, Japan, Vol. 42,No. 3, p. 730 (1993); Polymer Preprints, Japan, Vol. 42, No. 3, p. 736(1994); and Polymer Preprints, Japan, Vol. 42, No. 7, pp. 2490-2492(1993)].

[0210] Specifically, the reaction conditions for this sulfonation are asfollows. The polyarylene copolymer having no sulfonic acid groups isreacted with the sulfonating agent in the presence or absence of asolvent. Examples of the solvent include hydrocarbon solvents such asn-hexane, ether solvents such as tetrahydrofuran and dioxane, aproticpolar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide,N-methyl-2-pyrrolidone, and dimethyl sulfoxide, and halogenatedhydrocarbons such as tetrachloroethane, dichloroethane, chloroform, andmethylene chloride. Although the reaction temperature is notparticularly limited, it is generally from −50 to 200° C., preferablyfrom −10 to 100° C. The reaction period is generally from 0.5 to 1,000hours, preferably from 1 to 200 hours.

[0211] Thus, copolymers comprising units (A) and units (B) and havingsulfonic acid groups are obtained. The amount of the sulfonic acidgroups contained in the polymer is generally from 1 to 5 meq, preferablyfrom 1.5 to 4 meq, per g of the polymer. In other words, in the sulfonicacid-containing polymer of the invention, the number of sulfonic acidgroups contained therein is generally from 0.05 to 2, preferably from0.3 to 1.5, per unit (B) as a component of the polymer. When the numberof sulfonic acid groups is smaller than 0.05 per unit (B) as a componentof the polymer, proton conductivity is insufficient. On the other hand,when the number thereof exceeds 2 per unit (B), hydrophilicity isenhanced, so that the polymer is soluble in water or, even whenremaining water-insoluble, has reduced durability.

[0212] Desirable examples of the sulfonic acid-containing copolymersare:

[0213] copolymers which comprise preferably from 40 to 3 mol %, morepreferably from 30 to 5 mol %, structural units derived from4,4′-bis(4-chloro)diphenyl ether as units (A) and preferably from 60 to97 mol %, more preferably from 70 to 95 mol %, structural units derivedfrom 2,5-dichloro-4′-phenoxybenzophenone as units (B) and which hassulfonic acid groups in an amount of preferably from 1.5 to 3.5 meq,more preferably from 2.0 to 3.3 meq, per g of the polymer; and

[0214] copolymers which comprise preferably from 35 to 7 mol %, morepreferably from 30 to 8 mol %, structural units derived from4,4′-dichlorobenzophenone as units (A) and preferably from 65 to 93 mol%, more preferably from 70 to 92 mol %, structural units derived from2,5-dichloro-4′-phenoxybenzophenone as units (B) and which has sulfonicacid groups in an amount of preferably from 2.0 to 3.5 meq, morepreferably from 2.0 to 3.3 meq, per g of the polymer.

[0215] The amount of sulfonic acid groups to be incorporated can beeasily regulated by changing the amount (proportion) of monomer (A) tobe used as comonomers for forming aromatic compound units having a mainchain containing one or more electron-withdrawing groups therein.

[0216] The molecular weight of the unsulfonated polyarylene copolymer,from which the sulfonic acid-containing copolymers of the invention isobtained by the method described above, is generally from 1,000 to1,000,000, preferably from 1,500 to 200,000, in terms of weight-averagemolecular weight calibrated for that of standard polystyrenes. When themolecular weight thereof is lower than 1,000, the polymer not only hasinsufficient membrane-forming properties to give a membrane havingcracks, but has insufficient strength properties. On the other hand,when the molecular weight thereof exceeds 1,000,000, the polymer hasproblems of insufficient solubility, too high a solution viscosity, poorprocessability, etc.

[0217] The structure of the copolymers having sulfonic acid groups ofthe invention can be ascertained from an infrared spectra based on theS═O absorption appearing at 1,030 to 1,045 cm⁻¹ and at 1,160 to 1,190cm⁻¹, the C—O—C stretching appearing at 1,130 to 1,250 cm⁻¹, the C═Ostretching appearing at 1,640 to 1,660 cm⁻¹, etc. The composition ofsulfonic acid in copolymers can be determined by titration based onneutralization of the sulfonic acid or by elemental analysis. Thestructure of the copolymer can be ascertained also from a nuclearmagnetic resonance (¹H-NMR) spectrum based on the peak assigned toaromatic protons appearing at 6.8 to 8.0 ppm.

[0218] The proton-conductive membrane of the invention comprises thecopolymers containing sulfonic acid groups described above. However, thecopolymers containing sulfonic acid groups may be used in combinationwith an inorganic acid such as sulfuric acid or phosphoric acid, anorganic acid such as a carboxylic acid, an appropriate amount of water,etc.

[0219] Examples of methods for producing the proton-conductive membraneof the invention include a casting method and a melt forming method. Inthe casting method, the copolymers containing sulfonic acid groups ofthe invention is dissolved in solvents and the solution is formed intomembrane by casting.

[0220] Examples of the solvents used in the casting method includeaprotic polar solvents such as N,N-dimethylacetamide,N,N-dimethylformamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxideand alcohol solvents such as methanol.

[0221] The proton-conductive, membrane of the invention can be utilizedas a proton-conductive membrane in applications such as, e.g.,electrolytes for primary batteries, electrolytes for secondarybatteries, solid polymer electrolytes for fuel cells, display elements,various sensors, signal-transmitting media, solid capacitors, andion-exchange membranes.

[0222] The invention will be explained below in more detail by referenceto Examples, but the invention should not be construed as being limitedto the following Examples.

[0223] In the Examples, various properties were determined by thefollowing methods.

[0224] Weight-Average Molecular Weight

[0225] The number-average molecular weight or weight-average molecularweight of a precursor polymer to be sulfonated was determined, in termsof molecular weight calibrated for standard polystyrene, by gelpermeation chromatography (GPC) using tetrahydrofuran (THF) as asolvent.

[0226] Equivalent Weight for Sulfonic Acid

[0227] A polymer obtained was sufficiently washed with water until thewashing water became near neutral to thereby remove the remaining freeacid. The polymer washed was dried, and a given amount thereof wasweighed and dissolved in a THF/water mixed solvent. This solution wastitrated with a standard NaOH solution using phenolphthalein as anindicator. The equivalent weight for sulfonic acid of the polymer wasdetermined from the neutralization point.

[0228] Measurement of Proton Conductivity

[0229] A sample of membrane having a diameter of 13 mm which had beenplaced in an atmosphere having a relative humidity of 100% wassandwiched between platinum electrodes. This sandwich was placed in aclosed cell, which was examined with an impedance analyzer (HYP4192A)for the absolute value of cell impedance and for phase angle under theconditions of-a frequency of from 5 to 13 MHz, applied voltage of 12 mV,and temperature of 20° C., 50° C., or 100° C. The data obtained wereused to determine the complex impedance at an oscillation level of 12 mVwith a computer. The proton conductivity of the sample was calculatedtherefrom.

[0230] Tensile Strength

[0231] The tensile strength of a membrane obtained was measured byconventional tensile test at room temperature.

[0232] Behavior in Hot Water

[0233] The behavior of a membrane in hot water was observed by immersingthe membrane in 80° C. water for 24 hours and then examining themembrane for any changes in shape or state.

[0234] ◯: The membrane had a swell lower than 20% and retained theshape.

[0235] Δ: The membrane had a swell of 20% or higher and retained theshape.

[0236] X: The shape was not retained.

REFERENCE EXAMPLE 1

[0237] [Synthesis of 3,4′-bis(4-chlorobenzoylamino)diphenyl Ether]

[0238] A stirrer, three-way cock, and dropping funnel were attached to athree-necked flask containing 28.0 g (140 mmol) of 3,4′-diaminodiphenylether. The atmosphere in the flask was replaced with dry nitrogen.Thereto were added 200 ml of N-methylpyrrolidone and 28.3 g (280 mmol)of triethylamine. The resulting mixture was stirred. This flask wasplaced on an ice bath to cool the reaction mixture to 0° C. Thereafter,53.9 g (308 mmol) of 4-chlorobenzoyl chloride was added thereto throughthe dropping funnel over 30 minutes. This mixture was further stirred onthe ice bath for 30 minutes, subsequently allowed to gradually warm upto room temperature, and then continued to react for 12 hours. Theresulting reaction mixture was poured into 1.5 L of 4% aqueous sodiumhydrogen carbonate solution. The precipitate yielded was taken out byfiltration, washed with water, and then dried. The powder obtained wasdissolved in 300 ml of N-methylpyrrolidone and reprecipitated from 1liter of methanol. The product was recovered by filtration and dried toobtain 66 g (yield, 99%) of the target compound. It showed a meltingpoint of from 258 to 259° C.

REFERENCE EXAMPLE 2

[0239] [Synthesis of 4,4′-bis(4-chlorobenzoyl)diphenyl Ether]

[0240] A solution prepared by dissolving 42.6 g (250 mmol) of diphenylether and 87.5 g (500 mmol) of 4-chlorobenzoyl chloride in 75 ml ofmethylene chloride was placed in a three-necked flask equipped with adropping funnel, stirrer, and three-way cock. In a dry nitrogenatmosphere, a suspension obtained by dispersing 83.3 g (625 mmol) ofanhydrous aluminum chloride in 75 ml of methylene chloride was addeddropwise to the solution with stirring and under cooling at 10° C. orlower over 2 hours to react the reactants. The red-brown solutionobtained after the dropwise addition was continuously reacted at roomtemperature for 10 hours and then poured into an ice bath containinghydrochloric acid (a mixture of 2 kg of ice and 200 ml of aqueoushydrochloric acid solution) to cause precipitation. The precipitate wasrecovered by filtration and then dried. The powder obtained waspulverized and washed with 1 N aqueous hydrochloric acid solution, 5%aqueous sodium hydrogen carbonate solution, and distilled water. Thecrude crystalline product was dissolved in toluene and dehydrated byazeotropic distillation to obtain a concentrated solution. Theconcentrated solution was filtered through a hot Buchner funnel and thefiltrate was cooled. Thus, 49 g of the target compound was obtained ascrystals; the yield was 44%.

EXAMPLE 1

[0241] Into a three-necked flask equipped with a ball condenser and athree-way cock were introduced 193.5 g (540 mmol) of2,5-dichloro-4′-phenoxybenzophenone, 28.64 g (60 mmol) of3,4′-bis(4-chlorobenzoylamino)diphenyl ether, 11.7 g (78 mmol) of sodiumiodide, 11.8 g (18 mmol) of bis(triphenylphosphine)nickel dichloride,63.0 g (240 mmol) of triphenylphosphine, and 94.1 g (1.44 mol) of zinc.This flask was placed on a 70° C. oil bath and the atmosphere in theflask was replaced with nitrogen. Thereafter, 1,000 ml ofN-methyl-2-pyrrolidone was added to the mixture under a nitrogenatmosphere to initiate a reaction. The reaction mixture was reacted for20 hours and then diluted with 500 ml of N-methyl-2-pyrrolidone. Theresulting reaction mixture which had undergone polymerization was pouredinto a 1:10 mixture of hydrochloric acid and methanol to precipitatepolymer. The precipitates were washed, recovered by filtration, and thendried in vacuo. Thus, 173.3 g of a white powder was obtained. Thispolymer had a weight-average molecular weight of 123,000. The polymerobtained was formed into membrane using N-methyl-2-pyrrolidone ascasting solvent. This membrane was immersed in methanol, but no swellingwas observed.

[0242] 1,500 ml of concentrated sulfuric acid was added to 150 g of thepolyarylene copolymer obtained above. This mixture was stirred at roomtemperature for 24 hours to sulfonation. After the reaction, thereaction mixture was poured into a large amount of pure water toprecipitate the sulfonated polymer. The resulting polymer was washedwith water until the washing water became nearly neutral. Thereafter,the sulfonated polymer was recovered by filtration and dried in vacuo at90° C. 185.2 g of the sulfonated polymer was obtained. An IR spectrumthereof is shown in FIG. 1.

EXAMPLE 2

[0243] Reaction was conducted in the same manner as in Example 1, exceptthat the amounts of the feed monomers, i.e.,2,5-dichloro-4′-phenoxybenzophenone and3,4′-bis(4-chlorobenzoylamino)diphenyl ether, were changed to 172.00 g(480 mmol) and 57.27 g (120 mmol), respectively. As a result, a polymerwas obtained in an amount of 177.3 g. It had a weight-average molecularweight of 133,500.

[0244] A 150 g portion of the polymer was sulfonated in the same manneras in Example 1 to obtain 180.5 g of a sulfonated polymer. An IRspectrum thereof is shown in FIG. 2.

EXAMPLE 3

[0245] Reaction was conducted in-the same manner as in Example 1, exceptthat the amounts of the feed monomers, i.e.,2,5-dichloro-4′-phenoxybenzophenone and3,4′-bis(4-chlorobenzoylamino)diphenyl ether, were changed to 150.50 g(420 mmol) and 85.91 g (180 mmol), respectively. As a result, a polymerwas obtained in an amount of 184.1 g. It had a weight-average molecularweight of 145,200.

[0246] A 150 g portion of the polymer was sulfonated in the same manneras in Example 1 to obtain 176.2 g of a sulfonated polymer. An IRspectrum thereof is shown in FIG. 3.

EXAMPLE 4

[0247] Reaction was conducted in the same manner as in Example 1, exceptthat 26.84 g (60 mmol) of 4,4′-bis(4-chlorobenzoyl)diphenyl ether wasused in place of 28.64 g (60 mmol) of3,4′-bis(4-chlorobenzoylamino)diphenyl ether. As a result, a polymer wasobtained in an amount of 168.9 g. It had a weight-average molecularweight of 135,400. An IR spectrum of the polyarylene copolymer obtainedis shown in FIG. 4.

[0248] A 150 g portion of the polymer was sulfonated in the same manneras in Example 1 to obtain 188.6 g of a sulfonated polymer. An IRspectrum thereof is shown in FIG. 5.

EXAMPLE 5

[0249] Reaction was conducted in the same manner as in Example 1, exceptthat the amount of 2,5-dichloro-4′-phenoxybenzene was changed to 188.04g (525 mmol) and the amount of 3,4′-bis(4-chlorobenzoylamino)diphenylether was changed to 33.55 g (75 mmol). As a result, a polymer wasobtained in an amount of 170.0 g. It had a weight-average molecularweight of 138,200.

[0250] A 150 g portion of the polymer was sulfonated in the same manneras in Example 1 to obtain 187.5 g of a sulfonated polymer.

COMPARATIVE EXAMPLE 1

[0251] Polymerization reaction was conducted in the same manner as inExample 1, except that 214.9 g (600 mmol) of2,5-dichloro-4′-phenoxybenzophenone was used as the only monomer. As aresult, a polymer was obtained in an amount of 161 g. This polymer had aweight-average molecular weight of 192,800. It swelled considerably inmethanol.

[0252] A 150 g portion of the polymer was sulfonated in the same manneras in Example 1 to obtain 190.2 g of a sulfonated polymer.

COMPARATIVE EXAMPLE 2

[0253] Reaction was conducted in the same manner as in Example 1, exceptthat the amounts of 2,5-dichloro-4′-phenoxybenzophenone and3,4′-bis(4-chlorobenzoylamino)diphenyl ether were changed to 210.70 g(588 mmol) and 5.72 g (12 mmol), respectively. As a result, a polymerwas obtained in an amount of 165.1 g. It had a weight-average molecularweight of 158,800.

[0254] A 150 g portion of the polymer was sulfonated in the same manneras in Example 1 to obtain 188.6 g of a sulfonated polymer.

[0255] The polymers obtained in Examples 1 to 5 and Comparative Examples1 and 2 were dissolved in NMP in a concentration of 10%. The resultantsolutions each was cast on a glass plate and dried at 100° C. finally ina vacuum to remove the solvent. Thus, membranes were produced.Properties of the polymers obtained are summarized in Table 1. TABLE 1Equivalent Weight for Proton Tensile Behavior Sulfonic acid conductivitystrength in hot (meq/g) (S/cm) (kg/cm²) water Example 1 2.47 2.67 × 10⁻³686 ◯ Example 2 2.36 2.55 × 10⁻³ 745 ◯ Example 3 2.12 2.44 × 10⁻³ 980 ◯Example 4 2.39 2.34 × 10⁻³ 920 ◯ Example 5 2.23 2.35 × 10⁻³ 845 ◯Comparative 2.97 2.16 × 10⁻³ 320 X Example 1 Comparative 3.03 2.27 ×10⁻³ 345 X Example 2

EXAMPLE 6

[0256] Into a three-necked flask equipped with a ball condenser and athree-way cock were introduced 193.5 g (540 mmol) of2,5-dichloro-4′-phenoxybenzophenone, 15.1 g (60 mmol) of4,4′-dichlorobenzophenone, 11.7 g (78 mmol) of sodium iodide, 11.8 g (18mmol) of bis(triphenylphosphine)nickel dichloride, 63.0 g (240 mmol) oftriphenylphosphine, and 94.1 g (1.44 mol) of zinc. This flask was placedon a 70° C. oil bath and the atmosphere in the flask was replaced withnitrogen. Thereafter, 1,000 ml of N-methyl-2-pyrrolidone was added tothe mixture in a nitrogen atmosphere to initiate a reaction. Thereaction mixture was reacted for 20 hours and then diluted with 500 mlof N-methyl-2-pyrrolidone. The resultant reaction mixture which hadundergone polymerization was poured into a 1:10 mixture of hydrochloricacid and methanol to precipitate a polymer. The precipitate was washed,recovered by filtration, and then dried in vacuo. Thus, a white powderwas obtained in an amount of 153 g. This polymer had a weight-averagemolecular weight of 159,000. The polymer obtained was formed intomembrane using N-methyl-2-pyrrolidone as a casting solvent. Thismembrane was immersed in methanol, but no swelling was observed. An IRspectrum of the polymer obtained in shown in FIG. 6.

[0257] To 150 g of the polymer obtained above was added 1,500 ml ofconcentrated sulfuric acid. This mixture was stirred at room temperaturefor 24 hours to sulfonatation. After the reaction, the reaction mixturewas poured into a large amount of pure water to precipitate thesulfonated polymer. The resulting polymer was washed with water untilthe washing water came to near neutral pint. Thereafter, the sulfonatedpolymer was recovered by filtration and dried at 90° C. in vacuo. 179 gof the sulfonated polymer was thus yielded. An IR spectrum thereof isshown in FIG. 7.

EXAMPLE 7

[0258] Reaction was conducted in the same manner as in Example 6, exceptthat the amounts of 2,5-dichloro-4′-phenoxybenzophenone and4,4′-dichlorobenzophenone were changed to 182.7 g (510 mmol) and 22.6 g(90 mmol), respectively. As a result, a polymer was obtained in anamount of 150 g. It had a weight-average molecular weight of 143,500.

[0259] Sulfonation was conducted in the same manner as in Example 6 toobtain 175 g of a sulfonated polymer.

EXAMPLE 8

[0260] Reaction was conducted in the same manner as in Example 6, exceptthat the amounts of 2,5-dichloro-4′-phenoxybenzophenone and4,4′-dichlorobenzophenone were changed to 171.6 g (480 mmol) and 30.13 g(120 mmol), respectively. As a result, a polymer was obtained in anamount of 148 g. It had a weight-average molecular weight of 129,600. AnIR spectrum of the polymer obtained is shown in FIG. 8.

[0261] Sulfonation was conducted in the same manner as in Example 6 toobtain 171 g of a sulfonated polymer.

[0262] An IR spectrum of the sulfonated polymer is shown in FIG. 9.

EXAMPLE 9

[0263] Reaction was conducted in the same manner as in Example 6, exceptthat the amounts of 2,5-dichloro-4′-phenoxybenzophenone and4,4′-dichlorobenzophenone were changed to 154.0 g (420 mmol) and 45.2 g(180 mmol), respectively. As a result, a polymer was obtained in anamount of 142 g. It had a weight-average molecular weight of 63,800.

[0264] Sulfonation was conducted in the same manner as in Example 6 toobtain 162 g of a sulfonated polymer.

[0265] The polymers obtained in Examples 6 to 9 were dissolved in NMP ina concentration of 10%. The resultant solutions each was cast on a glassplate and dried at 100° C. finally in a vacuum to remove the solvent.Thus, membranes were produced. Properties of the polymers obtained aresummarized in Table 2. TABLE 2 Poly(4,4′- Equivalent benzophenone)weight of Tensile Behav- chain in sulfonic Proton strength ior copolymeracid conductivity (kg/ in hot (mol %) (meq/g) (S/cm) cm²) water Example6 10 2.59 2.56 × 10⁻³ 560 ◯ Example 7 15 2.48 2.36 × 10⁻³ 575 ◯ Example8 20 2.33 2.10 × 10⁻³ 623 ◯ Example 9 30 2.25 1.98 × 10⁻³ 750 ◯

EXAMPLE 10

[0266] Polymerization reaction was conducted under the same conditionsas in Example 6, except that 29.5 g (60 mmol) ofbis(4-trifluoromethylsulfonyloxyphenyl)hexafluoropropane was used inplace of 15.1 g (60 mmol) of 4,4′-dichlorobenzophenone.

[0267] Thus, a polymer was obtained in an amount of 165 g. It had aweight-average molecular weight of 294,000. An IR spectrum of thepolymer obtained is shown in FIG. 10.

[0268] Sulfonation was conducted in the same manner as in Example 6 toobtain 196 g of a sulfonated polymer.

[0269] An IR spectrum of the sulfonated polymer is shown in FIG. 11.

EXAMPLE 11

[0270] Polymerization reaction was conducted under the same conditionsas in Example 9, except that 88.6 g (180 mmol) ofbis(4-trifluoromethylsulfonyloxyphenyl)hexafluoropropane was used inplace of 45.2 g (180 mmol) of 4,4′-dichlorobenzophenone.

[0271] Thus, a polymer was obtained in an amount of 166 g. It had aweight-average molecular weight of 116,000. An IR spectrum of thepolymer obtained is shown in FIG. 12.

[0272] Sulfonation was conducted in the same manner as in Example 6 toobtain 180 g of a sulfonated polymer.

[0273] An IR spectrum of the sulfonated polymer is shown in FIG. 13.

[0274] The polymers obtained in Examples 10 and 11 were dissolved in NMPin a concentration of 10%. The resulting solutions each was cast on aglass plate and dried at 100° C. finally in a vacuum to remove thesolvent. Thus, membranes were produced. Properties of the polymersobtained are summarized in Table 3. TABLE 3 4,4′-Diphenyl- Equivalenthexafluoro- weight of Proton Tensile Behavior propane chain in sulfonicacid conductivity strength in hot Example No. copolymer (mol %) (meq/g)(S/cm) (kg/cm²) water 10 10 2.42 2.41 × 10⁻³ 520 ◯ 11 30 2.15 2.25 ×10⁻³ 575 ◯

EXAMPLE 12

[0275] Polymerization and post-treatment were conducted in the samemanners as in Example 6, except that 1.29 g (6 mmol) of4-chlorobenzophenone was used as a molecular weight modifier in additionto the monomers of 193.5 g (540 mmol) of2,5-dichloro-4′-phenoxybenzophenone and 15.1 g (60 mmol) of4,4′-dichloro-benzophenone.

[0276] Thus, a copolymer was obtained in an amount of 159 g. It had aweight-average molecular weight of 130,800.

[0277] Using 150 g of the polymer, sulfonation was conducted in the samemanner as in Example 6, and post-treatment, drying and membraneformation were also conducted in the same manners as in Example 6.Because the viscosity was low as compared with the solution viscosity ofthe polymerized and sulfonated polymer to which the molecular weightmodifier was not added, a membrane having smooth and good surface wasformed.

EXAMPLE 13

[0278] Polymerization and post-treatment were conducted in the samemanners as in Example 12, except that 2.58 g (12 mmol) of4-chlorobenzophenone was used in place of 1.29 g (6 mmol) of4-chlorobenzophenone.

[0279] Thus, a copolymer having controlled molecular weight was obtainedin an amount of 159 g. It had a weight-average molecular weight of94,600.

[0280] Using 150 g of the polymer, sulfonation was conducted in the samemanner as in Example 6, and post-treatment, drying and membraneformation were also conducted in the same manners as in Example 6.Because the viscosity was low as compared with the solution viscosity ofthe polymerized and sulfonated polymer to which the molecular weightmodifier was not added, a membrane having smooth and good surface wasformed. TABLE 4 4-Chloro- Weight Equivalent benzophe- average weight ofProton Tensile Behavior none molecular sulfonic conductivity strength inhot Example (mol %) weight acid (meq/g) (S/cm) (kg/cm²) water Example 121 130,800 2.55 2.56 575 ◯ Example 13 2 94,600 2.578 2.62 560 ◯

[0281] The polyarylene copolymers of the invention can be sulfonatedwhile easily regulating the amount of sulfonic acid groups to beincorporated. The sulfonic acid-containing polyarylene copolymersobtained are useful as a conductive membrane having high protonconductivity in a wide temperature range. The sulfonated polymer showsexcellent adhesion to substrates and electrodes, is not brittle, and hasexcellent strength and excellent resistance to hot water.

[0282] Consequently, the sulfonated polymers of the invention areutilizable as a conductive membrane in applications such as electrolytesfor primary batteries, electrolytes for secondary batteries, solidpolymer electrolytes for fuel cells, display elements, various sensors,signal-transmitting media, solid capacitors, and ion-exchange membranes.Therefore, the invention is of great industrial significance.

What is claimed is:
 1. A proton-conductive membrane comprising apolyarylene copolymer having sulfonic acid groups, the polyarylenecopolymer comprising (A) aromatic compound units having a main chaincontaining one or more electron-withdrawing groups therein and (B)aromatic compound units having a main chain containing noelectron-withdrawing groups therein.
 2. The proton-conductive membraneof claim 1, wherein the polyarylene copolymer comprises (A) 60 mol % orless than 60 mol % aromatic compound units having a main chaincontaining one or more electron-withdrawing groups therein and (B) 40mol % or less than 40 mol % aromatic compound units having a main chaincontaining no electron-withdrawing groups therein (provided that(A)+(B)=100 mol %, and (A) is not 0 mol %).
 3. The proton-conductivemembrane of claim 1, wherein the polyarylene copolymer comprises (A)from 60 to 0.01 mol % aromatic compound units having a main chaincontaining one or more electron-withdrawing groups therein and (B) from40 to 99.99 mol % aromatic compound units having a main chain containingno electron-withdrawing groups therein (provided that (A)+(B)=100 mol%).
 4. The proton-conductive membrane of claim 1, wherein the aromaticcompound units (A) having a main chain containing one or moreelectron-withdrawing groups therein are structures represented by thefollowing general formula (1):

wherein X and X′ each represents at least one divalentelectron-withdrawing group selected from the group consisting of —CO—,—CONH—, —(CF₂)_(p)—(wherein p is an integer of 1 to 10), —C(CF₃)₂—,—COO—, —SO— and —SO₂—; R¹ to R¹⁶ may be the same or different and eachrepresents a hydrogen atom, a halogen atom, an alkyl group, ahalogenoalkyl group, an allyl group, or an aryl group; and n is a numberof 0 or
 1. 5. The proton-conductive membrane of claim 1, wherein thearomatic compound units (B) having a main chain containing noelectron-attracting groups therein are structures represented by atleast one of the following general formulae (2) to (4):

wherein R¹⁷ to R²⁴ may be the same or different and each represents ahydrogen atom, an alkyl group, a halogen atom, a halogenoalkyl group, anaryl group, or a group represented by the formula

wherein X represents an electron-attracting divalent group; Y representsan electron-donating divalent group; and R²⁵ to R³³ each represents ahydrogen atom, an alkyl group, a halogen atom, or a halogenoalkyl group.6. The proton-conductive membrane of claim 1, wherein the polyarylenecopolymer comprises from 35 to 7 mol % structural units derived from4,4′-benzophenone as the aromatic compound units (A) having a main chaincontaining one or more electron-withdrawing groups therein and from 65to 93 mol % structural units derived from 4′-phenoxy-2,5-benzophenone asthe aromatic compound units (B) having a main chain containing noelectron-withdrawing groups therein and which has sulfonic acid groupsin an amount of from 2.0 to 3.5 meq per g of the polymer.
 7. Theproton-conductive membrane of claim 1, wherein the polyarylene copolymercomprises from 40 to 3 mol % structural units derived from4,4′-bis(benzoyl)diphenyl ether as the aromatic compound units (A)having a main chain containing one or more electron-withdrawing groupstherein and from 60 to 97 mol % structural units derived from4′-phenoxy-2,5-benzophenone as the aromatic compound units (B) having amain chain containing no electron-withdrawing groups therein (providedthat (A)+(B)=100 mol %) and which has sulfonic acid groups in an amountof from 1.5 to 3.5 meq per g of the polymer.
 8. The proton-conductivemembrane of claim 1, wherein the sulfonic acid groups are present in anamount of from 1 to 5 meq per gram of the polyarylene copolymer.
 9. Theproton-conductive membrane of claim 1, wherein the number of thesulfonic acid groups is from 0.05 to 2 per unit (B) as a component ofthe polyarylene copolymer.
 10. Polyarylene copolymer having sulfonicacid groups, comprising (A) from 60 to 0.01 mol % aromatic compoundunits having a main chain containing one or more electron-withdrawinggroups therein and (B) from 40 to 99.99 mol % aromatic compound unitshaving a main chain containing no electron-withdrawing groups therein(provided that (A)+(B)=100 mol %).
 11. The polyarylene copolymer ofclaim 10, wherein the aromatic compound units (A) having a main chaincontaining one or more electron-withdrawing groups therein arestructures represented by the following general formula (1):

wherein X and X′ each represents at least one divalentelectron-withdrawing group selected from the group consisting of —CO—,—CONH—, —(CF₂)_(p)—(wherein p is an integer of 1 to 10), —C(CF₃)₂—,—COO—, —SO— and —SO₂—; R¹ to R¹⁶ may be the same or different and eachrepresents a hydrogen atom, a halogen atom, an alkyl group, ahalogenoalkyl group, an allyl group, or an aryl group; and n is a numberof 0 or
 1. 12. The polyarylene copolymer of claim 1, wherein thearomatic compound units (B) having a main chain containing noelectron-attracting groups therein are structures represented by atleast one of the following general formulae (2) to (4):

wherein R¹⁷ to R²⁴ may be the same or different and each represents ahydrogen atom, an alkyl group, a halogen atom, a halogenoalkyl group, anaryl group, or a group represented by the formula

wherein X represents an electron-attracting divalent group; Y representsan electron-donating divalent group; and R²⁵ to R³³ each represents ahydrogen atom, an alkyl group, a halogen atom, or a halogenoalkyl group.